An image capture device can capture images from various perspectives, which may be useful for various objectives. As one example application, a mobile image capture device can be used to perform life logging, in which images are captured by the mobile image capture device over a period of time to document various events that occur during the user's daily life. Life logging can be performed to assist in memory retention in the elderly, to share the user's perspective or experience with other persons, or to simply document the various events that the user experiences so that the user can revisit such events in the future and enjoy their recollection. For example, a parent may enjoy reviewing images of their child blowing out candles on a birthday cake.
Thus, a mobile image capture device can be used to capture particular events in a person's life in much the same manner as the person would use a traditional camera to record such events. However, a mobile image capture device may provide the further benefit that the user does not have to actively operate a camera during the event to capture imagery of the event. Instead, the user is able to fully engage in and enjoy the event while the mobile image capture device captures imagery of the event. For example, the parent can enjoy and participate in their child blowing out candles on the birthday cake without the distraction of operating a camera, while still obtaining imagery of the scene to enjoy at a later time.
Furthermore, a mobile image capture device may be relatively more adept at capturing and curating imagery of candid moments versus a traditional camera. In particular, people commonly pose or otherwise unnaturally change their expression when a camera is used to take a photograph. In this sense, a mobile image capture device may be able to capture images which more accurately reflect true user experiences, such as laughter during conversation or a genuine but fleeting smile, while traditional cameras are more limited to the images in which the subjects adopt a common pose or “say cheese”.
As another example application, mobile image capture devices may be particularly advantageous where capturing a record of the user's perspective or associated events is a matter of public safety or has legal significance. For example, mobile image capture devices may be particularly advantageous in situations such as recording the perspective of a law enforcement officer when interacting with a member of the public.
However, a primary challenge faced by the design and use of mobile image capture devices is the resource-limited environment in which they operate. In particular, the design and use of mobile image capture devices is typically subject to the following constraints: a limited amount of memory to be used for image storage over a significant period of time; a limited amount of processing power or capability to continuously process imagery; a limited amount of energy available to operate over an extended period of time; and/or a limited amount of thermal power that can be dissipated (i.e., a device temperature that should not be exceeded so as to prevent overheating of the device or discomfort for the user, who may in some instances wear the mobile image capture device).
More particularly, mobile image capture devices typically store captured imagery at a local memory for at least an initial period of time until such imagery can be transferred or transmitted to another device. However, due to memory component cost, size, or other factors, the mobile image capture device typically will have only limited memory resources to dedicate toward storage of captured imagery. In the scenario in which the mobile image capture device is worn and operated for hours at a time (if not longer), the limited memory resources results in the device being unable to simply store a continuous stream of hours' worth of high resolution images. Furthermore, even if the mobile image capture device had sufficient memory resources to store such continuous stream of hours' worth of images, this would present an additional problem of requiring the user to cull a massive amount of images to try and pick the best or most desirable ones.
As another example, mobile image capture devices are typically powered by a battery. Thus, in the most common use cases, the limited power budget provided by a battery must be spread across hours of device operation, if not longer. Therefore, operations performed by the mobile image capture device which require or otherwise draw significant amounts of power must be limited or otherwise not continuously or commonly performed. As examples, the compression, storage, and transmission of images are the portions of a typical image processing cycle which consume the most significant amounts of power. Thus, in addition to a memory consumption problem, the compression and storage of massive amounts of imagery is an infeasible device design for the typical power budget provided by an on-board battery.
Similarly, despite advances in the size and ability of image processing chips, mobile image devices will still typically have a limited amount of computational power which can be employed at any given moment in time.
Further, the resource constraints described above are typically highly interrelated. For example, even given an unlimited power, computation, and memory budget, continuous performance of high power processing operations would cause the mobile image capture device to dissipate heat at a level that would cause discomfort for the user.
Thus, the memory, processing, power, and thermal constraints associated with a mobile image capture device collectively represent one of the most challenging limitations to the design and operation of a mobile image capture device.
As such, resource-efficient mobile image capture devices are desirable. In particular, mobile image capture devices that continuously capture imagery while providing additional advanced features in a resource-efficient manner are needed.